The present invention relates to a coupling system for connecting together components of a modular article, particularly a toy.
It is known that toys composed of a variety of parts which can be assembled together in different configurations have a certain educational value, as well as providing entertainment, and a wide variety of articles of this type is available on the market.
In order to be successfully used by children, and particularly young children, the connection together of the components of such an article should require a relatively low degree of manual dexterity and the application of relatively low forces to effect both connection and disconnection. However, it is desirable that the connection, once made, be relatively secure and rigid.
While a large number of connecting structures for this purpose have already been proposed, each of them is less than ideal in one respect or another.
Thus, in the coupling structures disclosed in U.S. Design Pat. No. 290,477, and U.S. Pat. Nos. 3,611,621; 4,685,892; and 4,582,447, the coupling elements, which include projections and receptacles, are composed of cylinders of constant cross section. In order for two parts to be connected together with these coupling structures, they must first be perfectly aligned and oriented so that the axes of the projections are coaxial with those of the receptacles. The connection and disconnection operations require movements which are exactly parallel to those axes and the connected state is maintained solely by frictional forces. As the coupling elements become worn, the connections tend to loosen.
The connecting structure disclosed in U.S. Pat. No. 4,253,268 is constituted by ball and socket connectors provided in the edges of flat parts to enable connected parts to be pivoted relative to one another. A rigid connection between the parts is, therefore, neither contemplated nor possible. Generally, the connection together of two parts with this structure would require two distinct steps because it would be extremely difficult to simultaneously align each ball with a respective socket. FIG. 2 of this patent discloses a connecting structure including a projecting element having a rounded tip and an axial slit which provides the tip with a certain degree of resiliency to enable the tip to be inserted into a cylindrical passage. This arrangement provides a shaft for supporting a part which is to be capable of rotating relative to the part which is provided with the cylindrical passage.
U.S. Pat. No. 2,972,833 discloses a plastic block assembly in which two parts are connected together via projecting elements having ball-shaped ends and receptacles having a generally circular cross section. It would appear from a consideration of the drawings of this reference that the connection and disconnection of two parts would require a considerable level of force. Moreover, in all of the embodiments illustrated in this reference, any one connecting surface is provided with only type of connecting element, which limits the variety of ways in which elements can be connected together.
U.S. Pat. Nos. 2,791,868 and 2,961,779 disclose connecting structures which include one part provided with a projecting element having an enlarged end and a second part provided with a receptacle, or aperture, in the form of two conic frustums whose small bases meet at the center of the part. In the case of U.S. Pat. No. 2,791,868, the tip of each projecting element has a rounded form. In view of the form of the projecting elements and the receptacles, it would appear that connection and disconnection operations would require a considerable level of force.
U.S. Pat. No. 2,649,803 discloses a connection structure composed of snap fasteners the connection and disconnection of which would appear to require a considerable level of force.
Finally, U.S. Pat. No. 3,230,643 discloses a connecting structure in which a rod carries, at one end, a coupling 50 of generally rectangular cross section provided with a laterally extending spherical boss via which the rod can be held in an associated tubular rod having an annular constriction which is engaged by the boss.